1. Field of the Invention:
This invention relates to gunsights and more particularly to rear sights that are rapidly adjustable in elevation.
2. Brief Description of the Prior Art:
Gunsights for ballistic weapons used at relatively long ranges, such as rifles and the like, have long been made adjustable in elevation in order to permit the marksman to aim directly at the target while the muzzle of the weapon is elevated to impart to the projectile the correct trajectory to strike the target. Various mechanisms have been provided to permit the rear sight to be raised or lowered to permit accurate aiming at a target of greater or lesser range, and such rear sights have often been provided with scales or the like to indicate to the marksman the range at which the projectile will cross the line of sight.
Generally, in shooting with firearms, which have a relatively high muzzle velocity, sight adjustment in elevation is necessary only at relatively long ranges, e.g, a few hundred yards. At short ranges such adjustment is not necessary because the trajectory of the bullet is approximately flat for a few tens of yards. However, with weapons having a relatively low muzzle velocity, such as those powered by compressed gas, the effect of the drop of the projectile is apparent at much shorter ranges. In particular, in the recently developed paintball sports, wherein participants fire pellets of marking fluid with compressed gas weapons, a rear sight adjustable in elevation is useful when shooting at a range of a few tens of yards. Because the participants are engaged at such relatively short ranges, a rear sight adjustable in elevation rapidly and conveniently is a useful accessory to the player's weapon.
A number of the adjustable rear sights that have been developed for rifles and the like have been equipped with means for adjusting the position of the sight, for holding the sight in the selected position and for indicating the range at which the projectile will cross the line of sight
Griffith, U.S. Pat. No. 684,226, discloses a sight comprising a base with upstanding flanges on each side and a sight leaf pivoted at its front end. An upturned rear end of the sight leaf carries a sighting aperture and forward-facing hooks which engage notches in the rear end of the side flanges of the sight base to retain the sight at its adjusted setting. In this sight the range can be read or estimated from the position of the sight-carrier relative to the flanges; however, adjustment of the range requires removing the gun from firing position.
Reising, U.S. Pat. No. 2,389,326, discloses a similar adjustable gunsight having a base member, upstanding side flanges and a sight leaf pivotably mounted within a body member and carrying a sighting aperture The sight leaf is provided with laterally extending projections which engage notches in the body member to fix the sight leaf at a selected angle, and a pointer which indicates the set range Adjustment of this sight also requires that the gun be removed from firing position to adjust range, and the range scale is visible only on the side of the flange.
Other inventors have attempted to provide rear sights which are rapidly adjustable in elevation.
Kennedy, U.S. Pat. No. 937,244, discloses an adjustable gunsight having a sight leaf pivoted at one end and carrying a rear sight aperture at the other. The angle of the sight leaf is adjusted by means of a lever attached to the pivoted end of the sight leaf. This lever comprises a plate having an arcuate aperture with an arcuate toothed rack mounted within the aperture. A spring-loaded detent engages the arcuate rack, and the plate is provided with indicia to indicate the range for which the sight is set. This sight permits rapid adjustment in elevation. However, the set range is only visible by inspecting the scale on the plate, which cannot be performed while the gun is held in firing position
Long, U.S. Pat. No. 410,422, discloses a gunsight having a sight leaf pivoted at one end and having a side lever for adjusting the elevation. This sight does not appear to be provided with positive detent means.
Dieffenbach, U.S. Pat. No. 533,003, discloses a rear sight adjustable in elevation by moving a sight leaf, pivoted at its rear end and having a sighting aperture at its front end. An arcuate notched rack is formed integral with the pivoted sighting leaf and a spring-loaded detent mechanism engages the teeth of the rack to hold the sight in position. A scale is provided on the side of the arcuate rack to indicate the target distance
Kennedy, U.S. Pat. No. 535,379, discloses a sight having a sight leaf pivoted at its front end and an arcuate rack attached to the sight leaf at the pivoted end The teeth of the arcuate rack engage the teeth of a straight rack affixed to a slider which is movable along the barrel of the gun, thus adjusting the sight in elevation. A second rack on the slide engages a pinion which is provided with a detent mechanism to hold the slide in the set position.
Kennedy, U.S. Pat. No. 592,740, discloses an adjustable sight having an adjustment mechanism similar to that disclosed in U.S. Pat. No. 535,379. The detent mechanism of this sight differs in that a spring loaded detent bears directly on the second linear rack of the slider to hold the sight in position.
Fischer, U.S. Pat. No. 658,709, discloses an adjustable sight having a sight leaf pivoted at its front end and an adjusting lever extending downward from one side of the sight leaf. The end of the lever engages a stepped slider which is moved along the barrel of the gun to adjust the angle of the sight leaf, while a spring latch holds the slider in the set position.
While these known adjustable sights provide for rapid adjustment, the distance scale is not visible to the marksman when he is looking through the sight aperture The mechanisms of the known rapidly adjustable sights also tend to be somewhat complex.
Accordingly, a need has continued to exist for a gunsight of simple construction which is rapidly and accurately adjustable in elevation while the marksman continues to hold the weapon in firing position.